Karl labs esatas thunholm



K. L. E. THUNHOLM.

EVAPORATING APPARATUS.

APPLICATION FILED AUG. 2. 1918.

1,324,417. Patented Dec. 9,1919.

KARL LABS ESAIAS THUNHOLM, 0F fiREBRO, SWEDEN.

EvAronA'rms APPARATUS.

Specification bf Letters Patent.

Patented Dec. 9, 1919.

Application filed August 2, 1918. Serial No. 247,960.

Orebro, Sweden, have invented certain new and useful Improvements inEvaporatin g Apparatus, of which the following is a spoolfication.

The evaporating apparatus which are at presenfgenerally employed forevaporating liquids coagulating at higher concentratlons are, as is wellknown to those skilled in the art, provided with a number of'outwardlyheated, narrow tubes located vertically in a closed vessel and throughwhich the liquid is forced from below and upward or v 1ce versa in suchmanner that the liquid principally flows on the inner walls of thetubesleaving the central portions of the same free 1n order that thegenerated steam may freelyescape and that the evaporating apparatus maythus have the highest possible capacity.

From theoretical point of view such evaporating apparatus have greatadvantages over other types of evaporators, but 1n several respects theyhave conslderable drawbacks which are due to the fact that the tubesurfaces, on evaporatin such liquids that have a tendency to coagu ateinconcentrated condition, very soon become covered with a heat insulatingdeposit making it necessary from time to time to stop the work of theapparatus for removing said deposit from the tubes.

My present invention now has for its object an evaporating apparatus,principally adapted to be used for evaporating suc liquids that have atendency to coagulate at higher concentrations, for instance wastesulphite cellulose lye, and in which, at the same time as it providesfor maintaining a large total steam generating liquid surface and freeescape for the generated vapors, a continuous cleaning of the heattransmitting surfaces is effected.

The apparatus consists of a closed receptacle comprising a number ofcompartments with double horizontal bottoms, the inner space betweensaid bottoms forming a heatin chamber. The double bottoms are provi edwith holes in which a collaror other communicating device is located,said collar extending a certain distance into the compartment to whichthe bottoms belong. Through this collar the vapors generated from theliquid having the form of a horizontal layer on theupper bottoms escapeto the next compartment and so on'until it leaves the receptacle througha discharge conduit. Each collar is at one place provided with a recessforming an overflow for tl18-llql11d from one compartment to the nextlower compartment. On a central Vertical shaft passlng throughoutv theapparatus there are located scrapers one for each compartment, saidscrapers being adapted to rotate with the shaft and to be displacedinthe longitudinal direction of the same for the purpose that they may draon the upper bottoms under the action 0 their whole weight and, thus,remove any deposits from sald' bottoms. In order to facilitate therotation of said scrapers they are preferably provided with a number ofrecesses, said recesses being located in such a manner that the recesseson one arm are located at different distances from the shaft than thoseon the other arm, in order that those parts of the bottom which are, dueto said recesses,

not acted upon by the one arm of the scraper will be acted upon by theother one. It is convenlent to locate the holes in the bottoms and alsothe collars zigzag. It is also suit- I able to locate the overflows atdiametrically opposite sides of adjacent collars. 1

In the present apparatus the liquid is, during the evaporation,maintained divided into a number of horizontal layers of uniformthickness. During the eva oration thus a uniform lowering of the who eliquid surface takes place and currents are formed within each li uidlayer from the point where fresh liquid is supplied to every point ofthe surface, these currents being most powerful in the direction to thepoint where the overflow takes place. Due to these currents the thinnerliquid being supplied from above will immediately be thoroughly mixedwith the more concentrated liquid on the bottom. Such a thorough andimmediate mixing is especially necessary on concentrating such liquidsthat have a tendency to coagulate at higher concentrations, since of aform of embodiment of the apparatus shown on the accompanying drawing.

' scraper. I The apparatus is built up by a number of V sections 1 eachof which forms a receptacle like body rovided with double bottoms2 and3. Tie upper receptacle is provided with a cover 5 and the lower onewith a bottom 6. Each receptacle is at its upper and lower ends providedwith a surround-. ing flange 4 and, when assembled, they rest on saidflanges which can be held together and tightened. in any convenientmanner. Centrally in the apparatus is journaled a vertical shaft 7located at its lower end in a bearing 8 and at its upper end in abearing 9. The shaft is provided at its-upper end with a belt pulley 10orany other means for imparting movement to the same. The shaft isrunnin through holes in the bottoms, the holes in the different pairs ofbottoms 2, 3 being preferably located zigzag. Through the holes of eachpair of bottoms 2, 3 is inserted a tube shaped collar 22 which istightly fastened to both bottoms. This collar extends to a certaindistance above the bottom 2 and is provided with a recess 14 formingoverflow for the liquid. The recesses 14= are preferably located at diametrically opposite sides of adjacent collars. On the shaft there arelocated a number of scrapers 11 one for each'bottom 2. They ou ht to bemade of a material which is sof ter than that of the bottoms 2 in orderthat the latter may not be worn out too easilyby the scrapers draggingon the same 7 during the rotation of the shaft. The

lit

scrapers are provided with recesses 12 in order to facilitate therotation of the same, said recesses being located on one arm of thescrapers at another distance from the shaft than on the other arm inorder that durin a whole turning of the scrapers, every point of thebottoms may be acted upon by the same. These recesses may be ofdifierent length and form on difi'erent scrapers as is shown in thedrawing. The scrapers ought, in the horizontal projection, to have theshape shown in Fig. 2, according to which they are at the ends curvedforward in the direction of movement in order that, on rotating againstthe liquid, a force component may be effected counteracting thecentrifugal forcefor preventing the liquid surface from becoming higherat the periphery than nearer to the center. The scrapers are located onthe shaft in such a manner that they can be freely displaced in thelongitudinal direction of the same. By this arrangement the scrapers areadapted to rest freely on the bottoms 2 andact on the same with theirwhole weight. For this purpose their hubs are provided with a teeter?groove 13, Fig. 2 and the shaft 7 with a duced into the heating chambersbetween the bottoms 2 and 3 through branch pipes 19. These pipesopeninto the heating chambers at such a distance above the bottoms that thewater of condensation cannot' After having flow off through the same.passed through the heating chamber and given off its heat to the liquidthrough the bottoms 2 the steam is led off through pipes 20 situated atthe same levelas the bottoms 3 so that the water of condensation is alsoled olf through the same. The pipes 20 open into a discharge tube 21.The concentrated liquid is led off through tube 17 at the lower part ofthe apparatus.

The apparatus works in the following manner: The liquid is suppliedthrough pipe 15 while the shaft 7 is rotated and the heating medium isintroduced through the tubes 18 and 19. The liquid rises 1n theuppermost compartment, at the same time as it partially evaporates,until a art of the same flows off through the over ow 14 and flows,through the collar 22 down on the bottom'2 of the adjacent compartmentwhere it evaporates and so on throughout the whole apparatus. The'vaporsgenerated are .led upward through the collars 22 without resistance andare then led off from the apparatus through the conduit 16. As statedabove, the scrapers have the object of not only removing any depositsfrom the bottoms 2, but also to impart motion to the liquid and thusmechanically-facilitate the escaping of the steam bubbles formed at saidbottoms. The liquid becomes gradually concentrated as it descends fromone bottom 2 to another, and finally when it reaches the bottom 6 it hasobtained the desired degree of concentration. The concentrated liquid isthen discharged through conduit 17. By varying the supply of liquid andof heating medium different degrees of concentration can be, obtained.The supply of heating medium to the different heating chambers can alsobe varied by means of valves provided in the pipes 19.

In the case that steam is used as a heating medium the tube 18 can befed with fresh steam, waste steam or wholly or partially with steamescaping from the conduit 16 after having been compressed so as to gethigher pressure and temperature. The heating may of course also beeffected by means of electrical resistances located in the heatingchambers.

It is obvious that the detail constructions shown may be varied withoutdeparting from the scope of the invention.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. The herein described evaporating apparatus, including a closedreceptacle composed bottoms of a plurality of sections formingcompartments and provided with double bottoms having openings therein,collars secured about the openings in the double bottoms and projectingthereabove into the adjacent compartment and provided in their upperedges with overflow recesses, a vertical r0.- tatable shaft in thereceptacle, means ior rotating'the shaft, scrapers on the shaft formoving about the upper portion of each double bottom, the spaces betweenthe double constituting heating chambers, means for controlling thepassage of a heating agent through the heating chambers,

means for supplying liquid to the upper part of the apparatus, and meansfor discharging concentrated liquid from the bottom of the apparatus.

2. The herein described evaporating apparatus, comprising a closed'receptacle, a number of compartments in said receptacle, horizontaldouble bottoms to each compartment, a heating chamber between saiddouble bottoms, holes through said double bottoms, a

collar assed through said holes and secured to the ottoms, said collarextending a. distance into the compartment, a recess in said collarsforming overflow for the'liquid to next compartment, said collars alsoforming means for leading off vapors from the compartments, a central,vertical shaft through the apparatus, means for rotating said shaft,scrapers on said shaft adapted to rotate with the same and to drag oneach upper bottom, recesses in said scrapers, means for supplying aheating agent to each heating are arranged in registration and theadjacent collars are, arranged in staggered relation.

4:. An apparatus as claimed in claim. 1 wherein the overflow recess ineach collar is arranged at a point diametrically opposite the recess inthe adjacent collar.

In testimony whereof I have aflixed my signature in presence of twowitnesses.

Witnesses:

- AxEL EHRNER, JACOB Bacon.

KARL LABS ESAIAS THUNHOLMt it

